U.S. patent application number 16/682481 was filed with the patent office on 2020-03-12 for i/o operation chaining to reduce communication time within execution of i/o channel operations.
The applicant listed for this patent is INTERNATIONAL BUSINESS MACHINES CORPORATION. Invention is credited to Michael James Becht, Edward W. Chencinski, Matthias Klein, Eric N. Lais, Bruce Ratcliff.
Application Number | 20200081627 16/682481 |
Document ID | / |
Family ID | 69007583 |
Filed Date | 2020-03-12 |
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United States Patent
Application |
20200081627 |
Kind Code |
A1 |
Chencinski; Edward W. ; et
al. |
March 12, 2020 |
I/O OPERATION CHAINING TO REDUCE COMMUNICATION TIME WITHIN
EXECUTION OF I/O CHANNEL OPERATIONS
Abstract
A set of memory access operations is obtained. The set of memory
access operations includes a plurality of memory access operations
to be chained, in which the plurality of memory access operations
are to be processed as an atomic unit. The plurality of memory
access operations are executed in a particular order, and one or
more results are provided.
Inventors: |
Chencinski; Edward W.;
(Poughkeepsie, NY) ; Ratcliff; Bruce; (Red Hook,
NY) ; Lais; Eric N.; (Georgetown, TX) ; Becht;
Michael James; (Poughkeepsie, NY) ; Klein;
Matthias; (Wappingers Falls, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
INTERNATIONAL BUSINESS MACHINES CORPORATION |
Armonk |
NY |
US |
|
|
Family ID: |
69007583 |
Appl. No.: |
16/682481 |
Filed: |
November 13, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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16025448 |
Jul 2, 2018 |
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16682481 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06F 3/0613 20130101;
G06F 13/4282 20130101; G06F 3/0673 20130101; G06F 2213/0026
20130101; G06F 13/1605 20130101; G06F 3/0659 20130101 |
International
Class: |
G06F 3/06 20060101
G06F003/06; G06F 13/42 20060101 G06F013/42; G06F 13/16 20060101
G06F013/16 |
Claims
1. A computer system for facilitating processing within a computing
environment, the computer system comprising: a memory; and a memory
controller in communication with the memory, wherein the computer
system is configured to perform a method, said method comprising:
obtaining, by the memory controller from an input/output (I/O)
device coupled to the memory controller via an I/O network, the
memory controller being external to the I/O network, a set of
memory access operations, the set of memory access operations
comprising a plurality of memory access operations to be chained,
wherein the plurality of memory access operations are received as a
group and are to be processed as an atomic unit; executing the
plurality of memory access operations in a particular order; and
providing one or more results of the set of memory access
operations.
2. The computer system of claim 1, wherein the obtaining comprises
obtaining a plurality of sets of memory access operations, and
wherein the executing comprises executing the plurality of memory
access operations of the plurality of sets of memory access
operations, wherein the plurality of memory access operations of
each set of memory access operations are performed in order within
the set of memory access operations.
3. The computer system of claim 2, wherein the executing the
plurality of sets of memory access operations comprises
simultaneously executing the plurality of sets of memory access
operations.
4. The computer system of claim 1, wherein the providing comprises:
coalescing a plurality of results from executing the plurality of
memory access operations of the set of memory access operations
into a single response; and providing the single response.
5. The computer system of claim 1, wherein the obtaining comprises
obtaining the set of memory access operations from a channel, and
wherein the executing comprises: determining whether there is a
node identifier available for the channel from which the set of
memory access operations is obtained; and performing the plurality
of memory access operations, based on determining there is an
available node identifier.
6. The computer system of claim 5, wherein the executing further
comprises refraining from performing the plurality of memory access
operations, based on determining there is no available node
identifier.
7. The computer system of claim 1, wherein the executing comprises:
determining an exception has occurred in performing a memory access
operation of the plurality of memory access operations; providing a
result that indicates the exception; and obtaining a
re-transmission of the memory access operation as a single
unchained operation.
8. The computer system of claim 1, wherein the method further
comprises processing one or more additional individual memory
access operations received from a same source from which the set of
memory access operations was obtained.
9. The computer system of claim 1, wherein the set of memory access
operations comprises a set of store operations to be performed in
one or more locations of the memory.
10. A computer program product for facilitating processing within a
computing environment, the computer program product comprising: at
least one computer readable storage medium readable by at least one
processing circuit and storing instructions for performing a method
comprising: obtaining, by the memory controller from an
input/output (I/O) device coupled to the memory controller via an
I/O network, a set of memory access operations, the set of memory
access operations comprising a plurality of memory access
operations to be chained, wherein the plurality of memory access
operations are received as a group and are to be processed as an
atomic unit; executing the plurality of memory access operations in
a particular order; and providing one or more results of the set of
memory access operations.
11. The computer program product of claim 10, wherein the obtaining
comprises obtaining a plurality of sets of memory access
operations, and wherein the executing comprises executing the
plurality of memory access operations of the plurality of sets of
memory access operations, wherein the plurality of memory access
operations of each set of memory access operations are performed in
order within the set of memory access operations.
12. The computer program product of claim 10, wherein the obtaining
comprises obtaining the set of memory access operations from a
channel, and wherein the executing comprises: determining whether
there is a node identifier available for the channel from which the
set of memory access operations is obtained; and performing the
plurality of memory access operations, based on determining there
is an available node identifier.
13. The computer program product of claim 10, wherein the executing
comprises: determining an exception has occurred in performing a
memory access operation of the plurality of memory access
operations; providing a result that indicates the exception; and
obtaining a re-transmission of the memory access operation as a
single unchained operation.
14. The computer program product of claim 10, wherein the method
further comprises processing one or more additional individual
memory access operations received from a same source from which the
set of memory access operations was obtained.
15. The computer program product of claim 10, wherein the providing
comprises: coalescing a plurality of results from executing the
plurality of memory access operations of the set of memory access
operations into a single response; and providing the single
response.
16. A computer-implemented method of facilitating processing within
a computing environment, the computer-implemented method
comprising: obtaining, by the memory controller from an
input/output (I/O) device coupled to the memory controller via an
I/O network, the memory controller being external to the I/O
network, a set of memory access operations, the set of memory
access operations comprising a plurality of memory access
operations to be chained, wherein the plurality of memory access
operations are received as a group and are to be processed as an
atomic unit; executing the plurality of memory access operations in
a particular order; and providing one or more results of the set of
memory access operations.
17. The computer-implemented method of claim 16, wherein the
obtaining comprises obtaining a plurality of sets of memory access
operations, and wherein the executing comprises executing the
plurality of memory access operations of the plurality of sets of
memory access operations, wherein the plurality of memory access
operations of each set of memory access operations are performed in
order within the set of memory access operations.
18. The computer-implemented method of claim 16, wherein the
obtaining comprises obtaining the set of memory access operations
from a channel, and wherein the executing comprises: determining
whether there is a node identifier available for the channel from
which the set of memory access operations is obtained; and
performing the plurality of memory access operations, based on
determining there is an available node identifier.
19. The computer-implemented method of claim 16, wherein the
executing comprises: determining an exception has occurred in
performing a memory access operation of the plurality of memory
access operations; providing a result that indicates the exception;
and obtaining a re-transmission of the memory access operation as a
single unchained operation.
20. The computer-implemented method of claim 16, further comprising
processing one or more additional individual memory access
operations received from a same source from which the set of memory
access operations was obtained.
Description
BACKGROUND
[0001] One or more aspects relate, in general, to input/output
(I/O) communications, and in particular, to processing of
input/output operations transmitted via input/output communication
devices.
[0002] One example of input/output communication devices are
channels. Channels may be implemented in cards that connect to a
computing system via one or more I/O links. For instance, IBM Z,
offered by International Business Machines Corporation, Armonk,
N.Y., provide channels that are implemented in cards that connect
to an IBM Z Central Electronics Complex (CEC) via a Peripheral
Component Interconnect express (PCIe) link, as examples. These
channels are used to access main memory within the Central
Electronics Complex.
[0003] The access path to/from main memory for channels providing
extended connectivity to storage and local area networks typically
crosses many components. Each component crossing results in
additional latency for memory accesses flowing to/from these types
of devices.
[0004] When an I/O operation is performed, it often involves
strings of individual single memory accesses which are to be
processed in strict sequence relative to one another. In many
cases, the external I/O device (e.g., channel) is to wait for the
completion of each memory access before initiating the next. When
such strings of serialized memory accesses are to be executed for a
single I/O operation, the overall latency for the sequence of round
trips between the channel and memory can add significant latency to
the I/O operation.
SUMMARY
[0005] Shortcomings of the prior art are overcome and additional
advantages are provided through the provision of a computer system
for facilitating processing within a computing environment. The
computer system includes a memory, and a memory controller in
communication with the memory. The computer system is configured to
perform a method. The method includes obtaining, by the memory
controller from an input/output (I/O) device coupled to the memory
controller via an I/O network, the memory controller being external
to the I/O network, a set of memory access operations. The set of
memory access operations includes a plurality of memory access
operations to be chained, in which the plurality of memory access
operations are received as a group and are to be processed as an
atomic unit. The plurality of memory access operations are executed
in a particular order, and one or more results of the set of memory
access operations are provided.
[0006] Computer-implemented methods and computer program products
relating to one or more aspects are also described and claimed
herein. Further, services relating to one or more aspects are also
described and may be claimed herein.
[0007] Additional features and advantages are realized through the
techniques described herein. Other embodiments and aspects are
described in detail herein and are considered a part of the claimed
aspects.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] One or more aspects are particularly pointed out and
distinctly claimed as examples in the claims at the conclusion of
the specification. The foregoing and objects, features, and
advantages of one or more aspects are apparent from the following
detailed description taken in conjunction with the accompanying
drawings in which:
[0009] FIGS. 1A-1C depict one example of a computing environment to
incorporate and use one or more aspects of the present invention,
as well as one example of processing associated with chained I/O
operations, in accordance with an aspect of the present
invention;
[0010] FIGS. 2A-2D depict one example of processing associated with
an exception in processing chained I/O operations, in accordance
with an aspect of the present invention;
[0011] FIGS. 3A-3D depict one example of processing associated with
dynamically changing a chained I/O operation to an unchained I/O
operation, in accordance with an aspect of the present
invention;
[0012] FIG. 4A depicts another example of a computing environment
to incorporate and use one or more aspects of the present
invention;
[0013] FIG. 4B depicts further details of the memory of FIG.
4A;
[0014] FIG. 5 depicts one embodiment of a cloud computing
environment; and
[0015] FIG. 6 depicts one example of abstraction model layers.
DETAILED DESCRIPTION
[0016] In accordance with one or more aspects, a capability is
provided to improve input/output (I/O) processing, and therefore,
system performance. In one aspect, the capability includes I/O
operation chaining, in which a plurality of memory accesses (e.g.,
of an I/O operation) are chained to reduce communications time
within execution of I/O operations. In one example, the chaining is
used with a communications protocol, such as a tunneled
communications protocol, an example of which is offered by
International Business Machines Corporation, Armonk, N.Y. The
tunneled protocol allows direct memory access (DMA) stores to flow
to memory without specific ordering rules, providing throughout
performance advantages. Although the tunneled protocol may not have
specific ordering rules, there may be architectural requirements
that specific individual stores are to be executed in order to
ensure data integrity. In such a scenario, the protocol specifies
that the stores are to be executed one at a time, waiting for the
tunneled response to return for each store in a sequence before
initiating the subsequent store. However, in accordance with an
aspect of the present invention, the performance advantages of the
tunneled protocol and similar protocols are extended by chaining
ordered sets of memory access operations used within, e.g., the
tunneled protocol, in which ordering locally within a set of
chained operations is enforced without incurring the disadvantage
of ordering all stores.
[0017] One embodiment of a computing environment to incorporate and
use one or more aspects of the present invention is described with
reference to FIG. 1A. In one example, computing environment 100
includes a Central Electronics Complex 102 coupled to one or more
I/O devices, such as channels 104, via a network 106. As examples,
channels 104 are Open Systems Adapters (OSA) providing local area
network (LAN) connectivity, and network 106 is a Peripheral
Component Interconnect express (PCIe) network; however, other types
of I/O devices, channels and/or networks are possible. In one
example, the tunneled communications protocol is defined over PCIe
and used in processing memory access operations that travel
between, e.g., a root complex of PCIe to system memory within the
Central Electronics Complex.
[0018] Central Electronics Complex 102 is, for instance, an IBM Z
Central Electronics Complex based on the z/Architecture, offered by
International Business Machines Corporation, Armonk, N.Y. One
embodiment of the z/Architecture is described in "z/Architecture
Principles of Operation," IBM Publication No. SA22-7832-10, March
2015, which is hereby incorporated herein by reference in its
entirety. Central Electronics Complex 102 includes, for instance,
one or more processors 110 coupled to system memory 112 (a.k.a.,
memory, main memory, main storage, central storage) via a memory
controller 114. Memory controller 114 is also coupled to PCIe
network 106 via one or more system buses 116.
[0019] Memory controller 114 includes, in accordance with an aspect
of the present invention, one or more chain execution units 130 to
process chained operations, as described herein. In one example, a
chain execution unit 130 includes a buffer 132 to queue memory
access operations (e.g., store operations) received from a channel
to be processed; a node identifier (NID) 134 to identify a set of
chained operations; and a recovery controller 136 to be used for
recovery, if needed or desired. In one example, chain execution
unit 130 is implemented as hardware; however, in other examples, it
may be implemented as software, firmware and/or a combination of
software, firmware and/or hardware.
[0020] Memory 112 may include, for instance, one or more programs
or applications 120, an operating system 122 (e.g., z/OS), one or
more computer readable program instructions 124, and/or data 126.
Computer readable program instructions 124 may be configured to
carry out functions of embodiments of aspects of the invention.
[0021] Computer Electronics Complex 102 may include and/or be
coupled to removable/non-removable, volatile/non-volatile computer
system storage media. For example, it may include and/or be coupled
to a non-removable, non-volatile magnetic media (typically called a
"hard drive"), a magnetic disk drive for reading from and writing
to a removable, non-volatile magnetic disk (e.g., a "floppy disk"),
and/or an optical disk drive for reading from or writing to a
removable, non-volatile optical disk, such as a CD-ROM, DVD-ROM or
other optical media. It should be understood that other hardware
and/or software components could be used in conjunction with
Computer Electronics Complex 102. Examples, include, but are not
limited to: microcode, device drivers, redundant processing units,
external disk drive arrays, RAID systems, tape drives, and data
archival storage systems, etc.
[0022] Computer Electronics Complex 102 may be operational with
numerous other general purpose or special purpose computing system
environments or configurations. Examples of well-known computing
systems, environments, and/or configurations that may be suitable
for use with Computer Electronics Complex 102 include, but are not
limited to, personal computer (PC) systems, server computer
systems, thin clients, thick clients, handheld or laptop devices,
multiprocessor systems, microprocessor-based systems, set top
boxes, programmable consumer electronics, network PCs, minicomputer
systems, mainframe computer systems, and distributed cloud
computing environments that include any of the above systems or
devices, and the like.
[0023] Data to be stored in system memory 112 is transmitted from
channel 104 over network 106 to memory controller 114. Memory
controller 114 performs the store operations and provides results
(e.g., status) back to channel 104 via network 106. To increase
efficiency in performing the store operations (or other memory
access operations), in accordance with an aspect of the present
invention, channel 104 transmits sets of chained operations to the
memory controller to be processed, as a group. Multiple memory
access operations may be transmitted, as a group, without waiting
for a response from an individual memory access operation,
increasing efficiency and performance. In one example, each group
or set of chained operations is processed as an atomic unit, in
which the group of chained operations is not considered complete
until, e.g., all of the operations in the group successfully
execute (e.g., without taking an exception or otherwise considered
complete). If, for instance, an operation of the group takes an
exception, chaining breaks and that operation and subsequent
operations are individually processed until, e.g., all operations
of the group are considered complete (preserving the atomic unit).
Subsequent to the group being considered complete, additional
processing of the results of the operations of the group and/or
other groups may be processed.
[0024] In one example, an operation chain controller 138 of channel
104 may be used to control the transmitting of chained operations
and receiving responses thereto. Operation chain controller 138 is
implemented, in one example, as a hardware component; however, in
other examples, it may be implemented as software, firmware and/or
a combination of software, firmware and/or hardware.
[0025] One embodiment of processing chained operations is described
with reference to FIGS. 1A-1C. Referring initially to FIG. 1A, 1 to
N (1:N) store operations (or other memory access operations) are
transmitted 140 from a channel (e.g., operation chain controller
138 of channel 104) or other I/O device, as a group, to a component
within the Central Electronics Complex, such as a memory controller
(e.g., memory controller 114). In one aspect, to alleviate the
latency of multiple memory accesses employed for a single I/O
operation, multiple memory accesses (of, e.g., the I/O operation)
may be transmitted as a group or a set, which includes a particular
order of operation for those accesses within the set. Further,
multiple I/O operations may be simultaneously initiated, each
specifying ordering in a nature which is encoded in, e.g., a
hardware component (e.g., a chain execution unit) residing much
closer to system memory than the channel that is initiating the
memory accesses. This enables the channel to initiate multiple sets
of chained, but otherwise independent memory accesses, avoiding the
time lost waiting for the completion responses of one access at a
time before initiating the next access.
[0026] In one example, to indicate the multiple memory accesses are
to be chained (e.g., considered as part of a set in a particular
order), an indicator (e.g., one or more bits in a PCIe header
accompanying the transmission of memory accesses) is set (e.g., to
one) to communicate the intent to chain the memory accesses.
[0027] Referring to FIG. 1B, based on the memory controller
obtaining (e.g., receiving, being provided, retrieving, etc.) the
set of memory accesses of an I/O operation, a selected chain
execution unit 130 of the memory controller executes 142 each
memory access operation in sequence. The sequencing is within the
set of memory accesses, and not between sets, in one example. To
perform the memory access operation, in one example, the chain
execution unit performs a store operation to store data in system
memory 112. As a store is complete, in one example, the chain
execution unit sends back 144 results (e.g., completion status) of
the individual operation to the I/O device (e.g., channel 104)
initiating the I/O operation. This is sent via, for instance,
network 106. In one example, operation chain controller 138 of the
initiating channel receives the results.
[0028] As shown in FIG. 1C, transmission 160 of the results
continues via, e.g., network 106 until complete. The results from
the multiple chained system memory access operations incur, e.g.,
the transport latency of close to just a single operation's round
trip to the system memory controller. When the channel (e.g.,
operation chain controller 138) receives the responses for all the
stores in the group (e.g., 1 to N), the channel can perform other
work using those results and/or continue to send additional groups
of operations. In one embodiment, the results may be coalesced
until all the memory accesses of the set are performed, and then
one result is returned to the channel. Many variations exist.
[0029] In one aspect, it is possible that one of the store
operations takes an exception. An example of this processing is
described with reference to FIGS. 2A-2D. Referring, initially, to
FIG. 2A, store operations 1 to N (or other memory accesses) are
transmitted 140, as a group, from a channel (e.g., channel 104) to
a host (e.g., a Central Electronics Complex). For example, the
store operations are transmitted from operation chain controller
138 of channel 104 to memory controller 114 via network 106. The
stores are buffered in a buffer (e.g., buffer 132) within a chain
execution unit 130 of memory controller 114.
[0030] Referring to FIG. 2B, the chain execution unit begins
performing the store operations 200, in order, and store J takes an
exception. The responses for stores 1 through J are transmitted 210
to the initiating device (e.g., operation chain controller 138 of
channel 104) via, e.g., network 106, as they complete.
[0031] As depicted in FIG. 2C, the remaining store responses are
transmitted 220 from memory controller 114 to the initiating
channel 104 via, e.g., network 106, but only stores 1 through J-1
are successful; stores J through N are aborted. Therefore, as shown
in FIG. 2D, stores J through N are re-transmitted 230, one at a
time, from channel 104 (e.g., operation chain controller 138) to
memory controller 114 for conventional (i.e., unchained) execution.
Each individual store operation is received in the memory
controller and serially executed 232. Each response for stores J
through N is returned 234 from memory controller 114 to the
initiating channel 104. In one embodiment, it is the responsibility
of operation chain controller 138 to receive the responses,
determine that certain accesses are to be re-transmitted,
re-transmit those memory accesses as individual operations, and
receive responses for the individual operations. When the responses
for stores 1:N are received, the group is considered complete,
preserving the atomic unit.
[0032] Further, in one example, it is the responsibility of
recovery controller 136 to ensure, when an operation fails, that
the operations that were chained together execute and complete
properly. This means that all of the operations have an associated
response. For instance, that the operations that were successfully
executed have the success indicated in their individual responses,
and the operations that failed or were not executed reflect that in
their responses, as well. The recovery controller performs clean up
after these operations complete and have sent back the proper
responses. The memory is to be left in a state that is consistent
with the responses that were sent back to the channel. When the
operations that failed to execute are individually resent, the
recovery controller is to have left the CEC in a cleaned up state,
such that these new separate operations will execute properly;
i.e., when the resent individual operations have all individually
completed their execution, the contents of the memory are the same
as they would have been had the operations all successfully
completed as part of the original chain.
[0033] In yet a further aspect, processing may dynamically and
automatically change from a chained operation to individual
operations, as described with reference to FIGS. 3A-3D. Referring
initially to FIG. 3A, stores 1 through N are transmitted 140 from a
device (e.g., channel 104) to the host (e.g., Central Electronics
Complex 102), and in particular, to a memory controller (e.g.,
memory controller 114) within the host. The memory controller
stores the obtained store operations in a buffer (e.g., buffer 132)
within a selected chain execution unit 130 of memory controller
114.
[0034] In one embodiment, as shown in FIG. 3B, the selected chain
execution unit 130 determines 300 whether there is an available
node identifier (NID) (e.g., NID 134) for this I/O domain (e.g.,
this set of memory accesses). For instance, in one embodiment,
based on receiving at least one memory access of a set of memory
accesses (e.g., store operations) to be performed for, e.g., an I/O
operation, the chain execution unit to perform the memory accesses
determines whether there is an available node identifier for the
set of memory accesses being transmitted from a channel. In
particular, in one embodiment, multiple channel sources for chained
operations could be simultaneously active to a single system memory
controller. Thus, the system memory controller is to keep the
operations from each channel's chain straight and distinct from
each other. To keep these separate, each source channel is assigned
a node identifier. A node identifier is, in one example, a number
that is used for ordering purposes for the host system cache bus
traffic that is initiated by the PBU (PCIe Bridge Unit) in, for
instance, a z processor. Requests and responses with the same NID
follow a strict set of ordering rules. Traffic with different NIDs
are not ordered relative to each other. In addition, the PBU can
freeze a particular NID, so that traffic to/from that NID is
rejected without affecting traffic from other NIDs.
[0035] In one embodiment, if the maximum allowable number of NIDs
in a PCIe link are exceeded, then any new memory accesses that
attempt to be chained are rejected and will come back as a series
of conventional unchained accesses. The system memory controller
has, in one implementation, state machines capable of tracking each
possible simultaneous chained operation set. These state machines
keep track of the execution of the chained system memory accesses
while they are resident in the system memory controller.
[0036] Referring to FIG. 3C, based on determining there is no
available NID, in one example, a no-NID response 310 is transmitted
from the memory controller (e.g., from the chain execution unit
130) back to the initiating channel 104 (e.g., to operation chain
controller 138). Thus, in one example, as shown in FIG. 3D, the
chained processing is automatically changed to unchained processing
(e.g., the indicator used to specify chaining is reset (e.g., to
zero)), and store operations 1 through N are re-transmitted 320
from channel 104 (e.g., from operation chain controller 138) to
memory controller 114 via, e.g., network 106, one at a time, for
conventional (i.e., unchained) execution. The memory controller
receives the individual store operations, serially performs 322 the
stores, and transmits 324 each response to the channel (e.g.,
operation chain controller 138). Since it is unchained execution,
channel 104 waits for a response from one memory access operation
of an I/O operation before sending the next memory access operation
of the I/O operation.
[0037] In accordance with one or more aspects, chaining provides
improved functionality for channels attached to processing systems
via, e.g., PCIe buses and other system buses, which are capable of
executing memory access operations. In one aspect, ordered sets of
operations used within, for instance, the tunneled protocol are
chained. A set of paired coordinated hardware elements is provided,
in one example, in which one element of each pair of elements is in
or close to an I/O channel (e.g., operation chain controller 138)
and the other element of each pair is in or close to the host
system memory controller (e.g., chain execution unit 130).
[0038] In one example, memory access operations are chained
together and transmitted over a link to execute in local order with
one another.
[0039] The channel element may initiate `K` individual serialized
memory access streams, each composed of `N` individual memory
access operations, which are transported to the element in the host
system memory controller via the system buses.
[0040] Sets of `N` memory access operations are identified which by
their nature are to be serialized in execution with the
communications protocol. In one example, a hardware element at the
source of these operations in the I/O channel (e.g., operation
chain controller 138) and a hardware element (e.g., chain execution
unit) within the memory controller are implemented. These hardware
elements are designed to cooperatively sequence through the passing
of the `N` selected serialized memory operations so that they are
chained together to execute as one atomic set. In one example, the
`N` operations are coded with an identifier when transmitted from
the channel, allowing the execution element in the memory
controller to associate them in a chain. The hardware element in
the system memory controller executes the `N` serial memory access
operations, one at a time, preparing responses back for each
operation in it's turn. As examples, responses can be returned
individually or coalesced into one combined response for the
chained set.
[0041] In one or more embodiments, multiple channel sources for
these chained operations could be simultaneously active to a single
system memory controller. Thus, the system memory controller is to
keep the operations from each channel's chain straight and distinct
from each other. To keep these separate, each source channel is
assigned a node identifier (NID).
[0042] In one aspect, the capability provides for individual
sequenced execution of the serialized operations from the element
in the system memory controller, and for executing many of these
ordered sets of memory accesses operations simultaneously using
unique NIDs to manage the individual sets distinctly from each
other.
[0043] Further, in one aspect, a mechanism is provided to issue
operations in the conventional non-chained manner when the set of
available NIDs has been exhausted.
[0044] Yet further, in one aspect, a capability is provided for the
channel to use currently unexploited bits within the PCIe header to
communicate the intent to chain any operations together that has
been so marked. Many variations exist.
[0045] In a further aspect, hardware failures may be detected,
while the ordered sets are in process, returning failing and
non-failing status to the individual operations as appropriate, and
allowing the retry of the failing individual access operations as
conventional individual non-chained operations. The failure of one
operation may be isolated from the other chained sets. In one
embodiment, the memory controller element decides whether a set of
chained operations is to be failed simply on the basis of whether
the operations failed to complete, and not as collateral damage
when a failure of another set of chained operations is
recovered.
[0046] In one aspect, the option of returning a single response for
a full set of successfully executed chained operations is
supported, in those cases where this is desired for improvements in
transport path bandwidth and latency.
[0047] In one aspect, the initiating and executing of such chained
sets of operations are provided, while also simultaneously
executing conventional unchained operations that are completely
ordered with operations from the same source, along with unchained
operations from the same source that have no ordering restrictions
at all.
[0048] Multiple I/O operations may be simultaneously initiated, and
an order is specified for the memory accesses of the operations,
which is encoded in, e.g., a hardware component residing much
closer to system memory than the channel initiating the memory
accesses.
[0049] The grouping and ordering of multiple I/O operations from
the same process to any memory location are provided, in one
aspect. The I/O operations may be to the same memory location or
various memory locations.
[0050] One or more aspects of the present invention are
inextricably tied to computer technology and facilitate processing
within a computer, improving performance thereof. For instance,
latency within I/O communications may be reduced, improving system
performance. As a particular example, one or more aspects save
transport time by allowing operations to be sent over the I/O
(e.g., PCIe) link, rather than waiting for the round trip of a
previous operation to complete; thus, overcoming an architectural
restriction of a transport protocol, and saving time by getting the
work closer to, e.g., memory faster, so that the memory access can
proceed earlier.
[0051] One example of using aspects of the present invention is, as
follows: An Open System Adapter (OSA) is an I/O channel providing
local area network (LAN) connectivity in IBM Z. When an inbound I/O
operation is completed, three simultaneous memory store operations
are to be executed in sequence before the communications to the LAN
completes--Store the SBAL (Storage Block Address List), Store the
SLSB (Storage List Status Block Byte(s), and Store status in the
SCB (SubChannel Bottom).
[0052] The round trip latency of each of these memory accesses
through PCIe and other system buses is typically over 1
microsecond. Executing these operations as a chained set in the
system memory, in effect, collapses 3 microseconds of round trips
into just 1 microsecond of a single round trip, since execution is
overlapped via chaining to hide the other 2 round trip travel
times; thus, saving 2/3 of the communications time between the OSA
channel and the memory controller.
[0053] Other types of computing environments may also incorporate
and use one or more aspects of the present invention, including,
but not limited to, emulation environments, an example of which is
described with reference to FIG. 4A. In this example, a computing
environment 35 includes, for instance, a native central processing
unit (CPU) 37, a memory 39, and one or more input/output devices
and/or interfaces 41 coupled to one another via, for example, one
or more buses 43 and/or other connections. As examples, computing
environment 35 may include a PowerPC processor offered by
International Business Machines Corporation, Armonk, N.Y.; and/or
other machines based on architectures offered by International
Business Machines Corporation, Intel, or other companies.
[0054] Native central processing unit 37 includes one or more
native registers 45, such as one or more general purpose registers
and/or one or more special purpose registers used during processing
within the environment. These registers include information that
represents the state of the environment at any particular point in
time.
[0055] Moreover, native central processing unit 37 executes
instructions and code that are stored in memory 39. In one
particular example, the central processing unit executes emulator
code 47 stored in memory 39. This code enables the computing
environment configured in one architecture to emulate another
architecture. For instance, emulator code 47 allows machines based
on architectures other than the z/Architecture, such as PowerPC
processors, or other servers or processors, to emulate the
z/Architecture and to execute software and instructions developed
based on the z/Architecture.
[0056] Further details relating to emulator code 47 are described
with reference to FIG. 4B. Guest instructions 49 stored in memory
39 comprise software instructions (e.g., correlating to machine
instructions) that were developed to be executed in an architecture
other than that of native CPU 37. For example, guest instructions
49 may have been designed to execute on a z/Architecture processor,
but instead, are being emulated on native CPU 37, which may be, for
example, an Intel processor. In one example, emulator code 47
includes an instruction fetching routine 51 to obtain one or more
guest instructions 49 from memory 39, and to optionally provide
local buffering for the instructions obtained. It also includes an
instruction translation routine 53 to determine the type of guest
instruction that has been obtained and to translate the guest
instruction into one or more corresponding native instructions 55.
This translation includes, for instance, identifying the function
to be performed by the guest instruction and choosing the native
instruction(s) to perform that function.
[0057] Further, emulator code 47 includes an emulation control
routine 57 to cause the native instructions to be executed.
Emulation control routine 57 may cause native CPU 37 to execute a
routine of native instructions that emulate one or more previously
obtained guest instructions and, at the conclusion of such
execution, return control to the instruction fetch routine to
emulate the obtaining of the next guest instruction or a group of
guest instructions. Execution of native instructions 55 may include
loading data into a register from memory 39; storing data back to
memory from a register; or performing some type of arithmetic or
logic operation, as determined by the translation routine.
[0058] Each routine is, for instance, implemented in software,
which is stored in memory and executed by native central processing
unit 37. In other examples, one or more of the routines or
operations are implemented in firmware, hardware, software or some
combination thereof. The registers of the emulated processor may be
emulated using registers 45 of the native CPU or by using locations
in memory 39. In embodiments, guest instructions 49, native
instructions 55 and emulator code 37 may reside in the same memory
or may be disbursed among different memory devices.
[0059] As used herein, firmware includes, e.g., the microcode of
the processor. It includes, for instance, the hardware-level
instructions and/or data structures used in implementation of
higher level machine code. In one embodiment, it includes, for
instance, proprietary code that is typically delivered as microcode
that includes trusted software or microcode specific to the
underlying hardware and controls operating system access to the
system hardware.
[0060] One or more aspects may relate to cloud computing.
[0061] It is to be understood that although this disclosure
includes a detailed description on cloud computing, implementation
of the teachings recited herein are not limited to a cloud
computing environment. Rather, embodiments of the present invention
are capable of being implemented in conjunction with any other type
of computing environment now known or later developed.
[0062] Cloud computing is a model of service delivery for enabling
convenient, on-demand network access to a shared pool of
configurable computing resources (e.g., networks, network
bandwidth, servers, processing, memory, storage, applications,
virtual machines, and services) that can be rapidly provisioned and
released with minimal management effort or interaction with a
provider of the service. This cloud model may include at least five
characteristics, at least three service models, and at least four
deployment models.
[0063] Characteristics are as follows:
[0064] On-demand self-service: a cloud consumer can unilaterally
provision computing capabilities, such as server time and network
storage, as needed automatically without requiring human
interaction with the service's provider.
[0065] Broad network access: capabilities are available over a
network and accessed through standard mechanisms that promote use
by heterogeneous thin or thick client platforms (e.g., mobile
phones, laptops, and PDAs).
[0066] Resource pooling: the provider's computing resources are
pooled to serve multiple consumers using a multi-tenant model, with
different physical and virtual resources dynamically assigned and
reassigned according to demand. There is a sense of location
independence in that the consumer generally has no control or
knowledge over the exact location of the provided resources but may
be able to specify location at a higher level of abstraction (e.g.,
country, state, or datacenter).
[0067] Rapid elasticity: capabilities can be rapidly and
elastically provisioned, in some cases automatically, to quickly
scale out and rapidly released to quickly scale in. To the
consumer, the capabilities available for provisioning often appear
to be unlimited and can be purchased in any quantity at any
time.
[0068] Measured service: cloud systems automatically control and
optimize resource use by leveraging a metering capability at some
level of abstraction appropriate to the type of service (e.g.,
storage, processing, bandwidth, and active user accounts). Resource
usage can be monitored, controlled, and reported, providing
transparency for both the provider and consumer of the utilized
service.
[0069] Service Models are as follows:
[0070] Software as a Service (SaaS): the capability provided to the
consumer is to use the provider's applications running on a cloud
infrastructure. The applications are accessible from various client
devices through a thin client interface such as a web browser
(e.g., web-based email). The consumer does not manage or control
the underlying cloud infrastructure including network, servers,
operating systems, storage, or even individual application
capabilities, with the possible exception of limited user-specific
application configuration settings.
[0071] Platform as a Service (PaaS): the capability provided to the
consumer is to deploy onto the cloud infrastructure
consumer-created or acquired applications created using programming
languages and tools supported by the provider. The consumer does
not manage or control the underlying cloud infrastructure including
networks, servers, operating systems, or storage, but has control
over the deployed applications and possibly application hosting
environment configurations.
[0072] Infrastructure as a Service (IaaS): the capability provided
to the consumer is to provision processing, storage, networks, and
other fundamental computing resources where the consumer is able to
deploy and run arbitrary software, which can include operating
systems and applications. The consumer does not manage or control
the underlying cloud infrastructure but has control over operating
systems, storage, deployed applications, and possibly limited
control of select networking components (e.g., host firewalls).
[0073] Deployment Models are as follows:
[0074] Private cloud: the cloud infrastructure is operated solely
for an organization. It may be managed by the organization or a
third party and may exist on-premises or off-premises.
[0075] Community cloud: the cloud infrastructure is shared by
several organizations and supports a specific community that has
shared concerns (e.g., mission, security requirements, policy, and
compliance considerations). It may be managed by the organizations
or a third party and may exist on-premises or off-premises.
[0076] Public cloud: the cloud infrastructure is made available to
the general public or a large industry group and is owned by an
organization selling cloud services.
[0077] Hybrid cloud: the cloud infrastructure is a composition of
two or more clouds (private, community, or public) that remain
unique entities but are bound together by standardized or
proprietary technology that enables data and application
portability (e.g., cloud bursting for load-balancing between
clouds).
[0078] A cloud computing environment is service oriented with a
focus on statelessness, low coupling, modularity, and semantic
interoperability. At the heart of cloud computing is an
infrastructure that includes a network of interconnected nodes.
[0079] Referring now to FIG. 5, illustrative cloud computing
environment 50 is depicted. As shown, cloud computing environment
50 includes one or more cloud computing nodes 52 with which local
computing devices used by cloud consumers, such as, for example,
personal digital assistant (PDA) or cellular telephone 54A, desktop
computer 54B, laptop computer 54C, and/or automobile computer
system 54N may communicate. Nodes 52 may communicate with one
another. They may be grouped (not shown) physically or virtually,
in one or more networks, such as Private, Community, Public, or
Hybrid clouds as described hereinabove, or a combination thereof.
This allows cloud computing environment 50 to offer infrastructure,
platforms and/or software as services for which a cloud consumer
does not need to maintain resources on a local computing device. It
is understood that the types of computing devices 54A-N shown in
FIG. 5 are intended to be illustrative only and that computing
nodes 52 and cloud computing environment 50 can communicate with
any type of computerized device over any type of network and/or
network addressable connection (e.g., using a web browser).
[0080] Referring now to FIG. 6, a set of functional abstraction
layers provided by cloud computing environment 50 (FIG. 5) is
shown. It should be understood in advance that the components,
layers, and functions shown in FIG. 6 are intended to be
illustrative only and embodiments of the invention are not limited
thereto. As depicted, the following layers and corresponding
functions are provided:
[0081] Hardware and software layer 60 includes hardware and
software components. Examples of hardware components include:
mainframes 61; RISC (Reduced Instruction Set Computer) architecture
based servers 62; servers 63; blade servers 64; storage devices 65;
and networks and networking components 66. In some embodiments,
software components include network application server software 67
and database software 68.
[0082] Virtualization layer 70 provides an abstraction layer from
which the following examples of virtual entities may be provided:
virtual servers 71; virtual storage 72; virtual networks 73,
including virtual private networks; virtual applications and
operating systems 74; and virtual clients 75.
[0083] In one example, management layer 80 may provide the
functions described below. Resource provisioning 81 provides
dynamic procurement of computing resources and other resources that
are utilized to perform tasks within the cloud computing
environment. Metering and Pricing 82 provide cost tracking as
resources are utilized within the cloud computing environment, and
billing or invoicing for consumption of these resources. In one
example, these resources may include application software licenses.
Security provides identity verification for cloud consumers and
tasks, as well as protection for data and other resources. User
portal 83 provides access to the cloud computing environment for
consumers and system administrators. Service level management 84
provides cloud computing resource allocation and management such
that required service levels are met. Service Level Agreement (SLA)
planning and fulfillment 85 provide pre-arrangement for, and
procurement of, cloud computing resources for which a future
requirement is anticipated in accordance with an SLA.
[0084] Workloads layer 90 provides examples of functionality for
which the cloud computing environment may be utilized. Examples of
workloads and functions which may be provided from this layer
include: mapping and navigation 91; software development and
lifecycle management 92; virtual classroom education delivery 93;
data analytics processing 94; transaction processing 95; and I/O
operation chaining processing 96.
[0085] Aspects of the present invention may be a system, a method,
and/or a computer program product at any possible technical detail
level of integration. The computer program product may include a
computer readable storage medium (or media) having computer
readable program instructions thereon for causing a processor to
carry out aspects of the present invention.
[0086] The computer readable storage medium can be a tangible
device that can retain and store instructions for use by an
instruction execution device. The computer readable storage medium
may be, for example, but is not limited to, an electronic storage
device, a magnetic storage device, an optical storage device, an
electromagnetic storage device, a semiconductor storage device, or
any suitable combination of the foregoing. A non-exhaustive list of
more specific examples of the computer readable storage medium
includes the following: a portable computer diskette, a hard disk,
a random access memory (RAM), a read-only memory (ROM), an erasable
programmable read-only memory (EPROM or Flash memory), a static
random access memory (SRAM), a portable compact disc read-only
memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a
floppy disk, a mechanically encoded device such as punch-cards or
raised structures in a groove having instructions recorded thereon,
and any suitable combination of the foregoing. A computer readable
storage medium, as used herein, is not to be construed as being
transitory signals per se, such as radio waves or other freely
propagating electromagnetic waves, electromagnetic waves
propagating through a waveguide or other transmission media (e.g.,
light pulses passing through a fiber-optic cable), or electrical
signals transmitted through a wire.
[0087] Computer readable program instructions described herein can
be downloaded to respective computing/processing devices from a
computer readable storage medium or to an external computer or
external storage device via a network, for example, the Internet, a
local area network, a wide area network and/or a wireless network.
The network may comprise copper transmission cables, optical
transmission fibers, wireless transmission, routers, firewalls,
switches, gateway computers and/or edge servers. A network adapter
card or network interface in each computing/processing device
receives computer readable program instructions from the network
and forwards the computer readable program instructions for storage
in a computer readable storage medium within the respective
computing/processing device.
[0088] Computer readable program instructions for carrying out
operations of the present invention may be assembler instructions,
instruction-set-architecture (ISA) instructions, machine
instructions, machine dependent instructions, microcode, firmware
instructions, state-setting data, configuration data for integrated
circuitry, or either source code or object code written in any
combination of one or more programming languages, including an
object oriented programming language such as Smalltalk, C++, or the
like, and procedural programming languages, such as the "C"
programming language or similar programming languages. The computer
readable program instructions may execute entirely on the user's
computer, partly on the user's computer, as a stand-alone software
package, partly on the user's computer and partly on a remote
computer or entirely on the remote computer or server. In the
latter scenario, the remote computer may be connected to the user's
computer through any type of network, including a local area
network (LAN) or a wide area network (WAN), or the connection may
be made to an external computer (for example, through the Internet
using an Internet Service Provider). In some embodiments,
electronic circuitry including, for example, programmable logic
circuitry, field-programmable gate arrays (FPGA), or programmable
logic arrays (PLA) may execute the computer readable program
instructions by utilizing state information of the computer
readable program instructions to personalize the electronic
circuitry, in order to perform aspects of the present
invention.
[0089] Aspects of the present invention are described herein with
reference to flowchart illustrations and/or block diagrams of
methods, apparatus (systems), and computer program products
according to embodiments of the invention. It will be understood
that each block of the flowchart illustrations and/or block
diagrams, and combinations of blocks in the flowchart illustrations
and/or block diagrams, can be implemented by computer readable
program instructions.
[0090] These computer readable program instructions may be provided
to a processor of a general purpose computer, special purpose
computer, or other programmable data processing apparatus to
produce a machine, such that the instructions, which execute via
the processor of the computer or other programmable data processing
apparatus, create means for implementing the functions/acts
specified in the flowchart and/or block diagram block or blocks.
These computer readable program instructions may also be stored in
a computer readable storage medium that can direct a computer, a
programmable data processing apparatus, and/or other devices to
function in a particular manner, such that the computer readable
storage medium having instructions stored therein comprises an
article of manufacture including instructions which implement
aspects of the function/act specified in the flowchart and/or block
diagram block or blocks.
[0091] The computer readable program instructions may also be
loaded onto a computer, other programmable data processing
apparatus, or other device to cause a series of operational steps
to be performed on the computer, other programmable apparatus or
other device to produce a computer implemented process, such that
the instructions which execute on the computer, other programmable
apparatus, or other device implement the functions/acts specified
in the flowchart and/or block diagram block or blocks.
[0092] The flowchart and block diagrams in the Figures illustrate
the architecture, functionality, and operation of possible
implementations of systems, methods, and computer program products
according to various embodiments of the present invention. In this
regard, each block in the flowchart or block diagrams may represent
a module, segment, or portion of instructions, which comprises one
or more executable instructions for implementing the specified
logical function(s). In some alternative implementations, the
functions noted in the block may occur out of the order noted in
the Figures. For example, two blocks shown in succession may, in
fact, be executed substantially concurrently, or the blocks may
sometimes be executed in the reverse order, depending upon the
functionality involved. It will also be noted that each block of
the block diagrams and/or flowchart illustration, and combinations
of blocks in the block diagrams and/or flowchart illustration, can
be implemented by special purpose hardware-based systems that
perform the specified functions or acts or carry out combinations
of special purpose hardware and computer instructions.
[0093] In addition to the above, one or more aspects may be
provided, offered, deployed, managed, serviced, etc. by a service
provider who offers management of customer environments. For
instance, the service provider can create, maintain, support, etc.
computer code and/or a computer infrastructure that performs one or
more aspects for one or more customers. In return, the service
provider may receive payment from the customer under a subscription
and/or fee agreement, as examples. Additionally or alternatively,
the service provider may receive payment from the sale of
advertising content to one or more third parties.
[0094] In one aspect, an application may be deployed for performing
one or more embodiments. As one example, the deploying of an
application comprises providing computer infrastructure operable to
perform one or more embodiments.
[0095] As a further aspect, a computing infrastructure may be
deployed comprising integrating computer readable code into a
computing system, in which the code in combination with the
computing system is capable of performing one or more
embodiments.
[0096] As yet a further aspect, a process for integrating computing
infrastructure comprising integrating computer readable code into a
computer system may be provided. The computer system comprises a
computer readable medium, in which the computer medium comprises
one or more embodiments. The code in combination with the computer
system is capable of performing one or more embodiments.
[0097] Although various embodiments are described above, these are
only examples. For example, computing environments of other
architectures can be used to incorporate and use one or more
embodiments. Further, different types of I/O devices and/or
networks may be used. Many variations are possible.
[0098] Further, other types of computing environments can benefit
and be used. As an example, a data processing system suitable for
storing and/or executing program code is usable that includes at
least two processors coupled directly or indirectly to memory
elements through a system bus. The memory elements include, for
instance, local memory employed during actual execution of the
program code, bulk storage, and cache memory which provide
temporary storage of at least some program code in order to reduce
the number of times code must be retrieved from bulk storage during
execution.
[0099] Input/output or I/O devices (including, but not limited to,
keyboards, displays, pointing devices, DASD, tape, CDs, DVDs, thumb
drives and other memory media, etc.) can be coupled to the system
either directly or through intervening I/O controllers. Network
adapters may also be coupled to the system to enable the data
processing system to become coupled to other data processing
systems or remote printers or storage devices through intervening
private or public networks. Modems, cable modems, and Ethernet
cards are just a few of the available types of network
adapters.
[0100] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting. As
used herein, the singular forms "a", "an" and "the" are intended to
include the plural forms as well, unless the context clearly
indicates otherwise. It will be further understood that the terms
"comprises" and/or "comprising", when used in this specification,
specify the presence of stated features, integers, steps,
operations, elements, and/or components, but do not preclude the
presence or addition of one or more other features, integers,
steps, operations, elements, components and/or groups thereof.
[0101] The corresponding structures, materials, acts, and
equivalents of all means or step plus function elements in the
claims below, if any, are intended to include any structure,
material, or act for performing the function in combination with
other claimed elements as specifically claimed. The description of
one or more embodiments has been presented for purposes of
illustration and description, but is not intended to be exhaustive
or limited to in the form disclosed. Many modifications and
variations will be apparent to those of ordinary skill in the art.
The embodiment was chosen and described in order to best explain
various aspects and the practical application, and to enable others
of ordinary skill in the art to understand various embodiments with
various modifications as are suited to the particular use
contemplated.
* * * * *